The use of a velocity profile to control the motion of an elevator car is well known. See, for instance, U.S. Pat. No. 4,751,984 entitled "Dynamically Generated Adaptive Elevator Velocity Profile", as well as pending U.S. Patent Application Ser. No. 07/375,429 entitled "Elevator Speed Dictation System", both of which are owned by the Assignee hereof and both of which disclose how to generate velocity or motion profiles for an elevator car.
Motion control of an elevator car involves regulating the movement of an elevator car from an origin floor to a destination floor. Car motion may be controlled by using jerk rates, acceleration rates and deceleration rates to regulate the rate of change of acceleration and velocity to maintain the forces acting on a passenger within the car within a subjective comfort zone. A typical motion profile also includes a maximum desired speed which the elevator car will attain during longer floor runs, also known as the contract speed. A feedback loop is used to regulate the car motion especially as the car decelerates to a stop as it approaches the destination floor.
On short runs elevator cars usually do not achieve their desired maximum speed. On longer runs an elevator car travels at maximum speed after it is accelerated to that speed once it leaves the origin floor and it continues at maximum speed until it must decelerate to stop at the destination floor. For both short runs and longer runs the overall flight time, the time period extending from when the elevator doors are closed at the origin floor until the doors open at the destination floor, may be reduced if the elevator car accelerates and decelerates faster either allowing the car to reach a higher speed on a short run or to operate for longer periods at maximum speed in a longer run. By reducing the flight time between floors, the waiting time for passengers awaiting arrival of an elevator car is reduced, the travel time for passengers in the elevator car is reduced, and the overall capacity of the elevator system to move people is increased.
During periods of reduced traffic, the jerk, acceleration and deceleration rates may be reduced increasing the flight time between floors enhancing the smoothness of the ride and the comfort level of the elevator car passenger without increasing the waiting time for passengers awaiting an elevator car beyond a desired level and while maintaining sufficient elevator system capacity to serve all the passengers.
Previously, the designers of elevator systems have preselected a particular motion profile for each elevator system. This motion profile would represent a compromise between fast flight times and increased capacity as opposed to slow flight time and increased comfort. The profile selected for each elevator might even vary based upon the particular market where the elevator would be installed and the expectations of passengers on a desired comfort level and the need for faster service. For instance, Far Eastern passengers prefer a motion profile with relatively slow jerk and acceleration rates such that a smoother, more comfortable ride is obtained and are more willing to wait longer for the elevator car to arrive than other passengers. The typical North American passenger has been less concerned with comfort and is more concerned with fast flight times and decreased waiting time and, therefore, would prefer to have the elevator car operated at a faster profile with slightly less passenger comfort due to the higher acceleration and jerk rates.